The present invention relates to an apparatus for scanning an object to be scanned with a radiation beam. Such an apparatus may be used to record an image on an image recording substrate or probe for information about an image or object to be scanned by collecting energy from the object with a radiation detector.
The present invention particularly relates to a scanning apparatus having a scanning beam deflector for scanning a beam along a scan axis, and a movable carriage, movable along a motion axis for moving the scanning beam deflector continuously or incrementally along the motion axis. Such a beam deflector apparatus may be characterized e.g. by a rotating mirror being rotated about a rotation axis by a spinner motor. An input beam incident to the rotating mirror is reflected radially away from the mirror in a sweeping scan motion such that a region of an object to be scanned is traversed by the rotating mirror output beam. The introduction of linear motion to the rotating mirror and spinner motor attached to the movable carriage provides for scanning the object to be scanned in two dimensions with a series of scans.
In addition to a radiation beam deflector and movable carriage, a scanning apparatus typically comprises a radiation source for generating an incident beam, input optics for shaping the incident beam, output optics for shaping the output beam, a linear drive apparatus for moving and guiding the carriage along the motion axis, a driver and controller for driving the scanning and carriage motions in synchronization and a master controller for sending receiving and or storing scan data.
Scanning apparatuses at least date back to 1928 when Schroter et at. in U.S. Pat. No. 1,746,407 showed an internal drum scanner having a thin walled partial cylinder for holding an object to be scanned against it's inner circumferential surface. Beam scanning is provided by rotating optical element, rotating about the cylinder longitudinal axis which reflects an incident beam directed along the cylinder longitudinal axis radially outward toward the object to be scanned. The internal drum provides a scan surface having constant radial distance from the rotation axis such that a lens placed in the beam path either before or after the beam deflector can be used to focus the beam energy to a fine spot at the surface of the object to be scanned.
In the Schroter embodiment, the entire drum and object to be scanned are mounted to a movable carriage and are traversed along a linear motion axis parallel to the longitudinal axis of the drum, moving the object to be scanned past the rotating optical element which remains in a fixed position with respect to the motion axis. This embodiment requires moving the drum over the entire scan length necessitating a scanning apparatus which is substantially longer that the object to be scanned adding significant cost to the structural support and enclosure elements and presenting substantial difficulties in supporting and balancing the rotating elements when long scan lengths are considered. Furthermore, the friction slide and lead screw linear drive apparatus require a high torque drive motor. These elements add cost which increases with scan length and improved motion precision requirements.
Pugsley in U.S. Pat. No. 3,875,587 and Matsushita in GB Pat. No. 1,185,115 each teach the improvement of suspending a movable carriage within an internal drum and mounting a rotating optical element, spin motor and spin motor encoder on the carriage for linear motion within the drum. In this embodiment, the drum and object to be scanned remain stationary while the more compact carriage and beam deflector elements are moved linearly. This embodiment reduces the mass of the moving elements thereby reducing friction allowing smaller, less costly linear motion elements to be employed.
In the Pugsley and Matsushita embodiments the overall length of the scanning apparatus may be reduced by translating the smaller carriage and beam deflector elements instead of the larger drum. However, the apparatus length still exceeds the scan length due to the need for mounting a radiation source and linear drive components outside the linear travel range of the carriage. The added apparatus length for components outside the linear travel range of the carriage adds cost to structural and enclosure elements and may cause the apparatus be prohibitively long, reaching weight and floor space limits for office and light industrial equipment standards when very large objects, e.g. newspaper pages, are to be scanned.
It is accordingly, a general object of the present invention to provide an improved scanning apparatus with reduced cost and weight and with an apparatus length substantially equal to the scan length of the object to be scanned.
It is a specific object of the present invention to provide a scanning apparatus having a self-propelled movable carriage.
It is a further object of the present invention to provide a scanning apparatus having a self-propelled movable carriage with attached radiation source, beam deflector and scanner diver and controller for synchronizing scan and linear motions.